He gave me some more information.
"Abstract
This specification covers nominally anhydrous denatured fuel ethanol intended for blending with unleaded or leaded gasolines for use as a spark-ignition automotive engine fuel. Denatured fuel ethanol shall conform to the specified performance requirements for the following: ethanol content, methanol, solvent-washed gum, water content, denaturant content, inorganic chloride content, copper content, acidity, pHe, sulfur content, sulfate content, appearance, and specific gravity.
The only denaturants used for fuel ethanol shall be natural gasoline, gasoline components, or unleaded gasoline at the minimum concentration prescribed.
Prohibited denaturants include methanol which does not meet the specified requirement, pyrroles, turpentine, ketones, and tars (high-molecular weight pyrolysis products of fossil or nonfossil vegetable matter). Sampling, containers, and sample handling techniques, and the test methods for determining conformance to the specified requirements are given."
ASTM D4806 - 14 Standard Specification for Denatured Fuel Ethanol for Blending with Gasolines for Use as Automotive Spark Ignition Engine Fuel